What are vegetable oils as fuel?

SVO – straight vegetable oil used as diesel fuel (usually new oil, fresh, uncooked).
PPO – pure plant oils, same as SVO: PPO is the term most often used in Europe.
WVO – waste vegetable oil (used cooking oil, “grease”, fryer oil, probably including animal fats or fish oils from the cooking).
UCO – used cooking oil (what we called it in the first place until everyone started calling it WVO – even if it wasn’t necessarily all vegetable).

The oil produced from oil plants through pressing, extraction or comparable procedures, crude or refined but chemically unmodified, when compatible with the type of engines involved and the corresponding greenhouse gas emissions requirements.

Vegetable oil can be used as an alternative fuel in diesel engines and in heating oil burners. When vegetable oil is used directly as a fuel, in either modified or unmodified equipment, it is referred to as straight vegetable oil (SVO) or pure plant oil (PPO).

Conventional diesel engines can be modified to help ensure that the viscosity of the vegetable oil is low enough to allow proper atomization of the fuel.

This prevents incomplete combustion, which would damage the engine by causing a build-up of carbon. Straight vegetable oil can also be blended with conventional diesel or processed into biodiesel or bioliquids for use under a wider range of conditions.

Virgin vegetable oil, also termed pure plant oil or straight vegetable oil, is extracted from plants solely for use as fuel. In contrast to used vegetable oil, is not a byproduct of other industries, and thus its prospects for use as fuel are not limited by the capacities of other industries.[citation needed] Production of vegetable oils for use as fuels is theoretically limited only by the agricultural capacity of a given economy.

Rudolf Diesel was the father of the engine which bears his name. His first attempts were to design an engine to run on coal dust, but later designed his engine to run on vegetable oil. The idea, he hoped, would make his engines more attractive to farmers having a source of fuel readily available. In a 1912 presentation to the British Institute of Mechanical Engineers, he cited a number of efforts in this area and remarked, “The fact that fat oils from vegetable sources can be used may seem insignificant today, but such oils will become in course of time of the same importance as some natural mineral oils and the tar products are now.”